#include <stdio.h>
int main()
{
	int x,y;
	scanf("%d",&x);
	if(x<1)
		y=x;
	else if(x<10)	//x>=1&&x<10
		y=2*x-1;
	else
		y=3*x-11;
		
	printf("%d",y);
	return 0;
}